Horswill P, O'Sullivan O, Phoenix GK, Lee JA, Leake JR. Base cation depletion, eutrophication and acidification of species-rich grasslands in response to long-term simulated nitrogen deposition. Environmental Pollution. 2008  ;155:336-349.

Arroniz-Crespo M, Leake JR, Horton P, Phoenix GK. Bryophyte physiological responses to, and recovery from, long-term nitrogen deposition and phosphorus fertilisation in acidic grassland. New Phytologist . 2008  ;180:864-874.